Commercial refrigerator with energy saving mode

ABSTRACT

A commercial refrigerator for energy savings and a method to operate thereof. The refrigerator comprises a cabinet, the cabinet with a first cavity with an inner part, an access to said inner part and an air chamber set in the inner part, the air chamber comprising a fan which makes the air pass through an evaporator, a thawing resistance which thaws the evaporator, a cover with first slits which allow an air flow emanating from the first cavity towards the inner part of said air chamber and second slits that allow air flow cooled by the evaporator emanating from the inner part of said air chamber to the first cavity; temperature sensors set within the inner part of the air chamber, a first temperature sensor set between the first slit and the fan and a second temperature sensor set between the evaporator and the second slits, said sensors connected to an electronic control. 
     The method collects temperature data from a sensor and temperature data from another sensor within an air chamber; compares the data from one sensor to the data from the other sensor to obtain a temperature value and calculates the stability of the data from the comparison; averages said data such that the temperature obtained is presumed as very close to the temperature of the products within the inner part of a chamber; de-energize a compressor by means of an electronic control.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(a) to MexicanPatent Application Serial No. MX/a/2015/013583, filed Sep. 14, 2015, thecontents and disclosure of which is hereby incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

Present invention lies in the field of refrigerators, particularlycommercial refrigerators which may be found in convenience, self-serviceor supermarket stores, which store cans, containers or receptacles withsome liquid; the commercial refrigerators consist of a translucent doorwhich allows glancing into their inner part, and as opposed to householdrefrigerators, the commercial refrigerators do not have a freezer as aseparate compartment from the fresh food one. It is very desirable forthese commercial refrigerators to be able to provide their depositary orowner, a type of energy savings, knowing that the electrical energy thatthese appliances consume directly impacts the indirect operational costsof the convenience, self-service or supermarket store, thus low energyconsumption is highly desirable, to such an extent that some conveniencestore owners unplug or disconnect these appliances when closing thestore, the problem they then face is that sometimes the products are“warm” upon opening the store, which is bothersome to customers, orwhich in some cases could damage conservation of the liquids needing tobe conserved, and thus the need arises of providing a commercialrefrigerator with the necessary means that it may turn on an energysavings mode when the store is closed or there is no clientele presentand reactivate itself prior to store opening or its contents are soughtby a customer desiring a beverage at an appropriate temperature.

BACKGROUND OF THE INVENTION

Various efforts have been taken in the field of commercial refrigeratorsto overcome the above described problem, a document worth studying is US4417 450 by Morgan et al, in which a commercial refrigerator isdescribed with electronic control means based on a microcontrollerpaired with a hand device which allows communicating with themicrocontroller to thus modify operation parameters, without having thepossibility of modifying the logic or programming of themicrocontroller, and thanks to a series of sensors the microcontrollermay determine if it is in a high sale stage, in which case it candetermine to change its temperature parameters to ensure correct innercooling of the beverages to be sold, it also consists with a clock whichallows programming its periodic cooling functions as well as the periodsof continuous compressor operation which are used for recovering thetemperature right after a low or no sales period. The above patent hasthe inconvenience of basing the energy savings functions on an agendatype, where the user can program what days and hours have low or nosales; which can vary, if this happens it needs to be reprogrammedthrough the hand held device, which is inconvenient, being obvious thatthe technician needs to be called in or to have the handheld deviceavailable, as well as needing to know how to use it, additionally thesystem cannot adapt itself to the sale conditions, being highlyinconvenient by requiring constant parameter modifications by the user.

Another document of particular interest is U.S. Pat. No. 7,200,467 bySchanin et al describes a method and apparatus for handling energyconsumption which monitors the refrigerator door at all times, noting ifits open or closed as well as its opening frequency, also having meansof monitoring air temperature in the refrigerator's interior, which arecompared at all times with the programmed values (set point); itreferences that it consists with at least two operation modes, a normalas well as an energy savings mode, so that depending on if the door isopen, it can determine changing the operation mode, in anotherembodiment it can also consider the inner air temperature of therefrigerator to determine being in a determined operation mode; thisdocument is based on monitoring the air temperature yet not giving muchimportance to the objects stored inside, which is inconvenient to thecustomer knowing that if the temperature near the sensor is within theparameters, but the lower part of the refrigerator is filled with roomtemperature drinks, the sensor will not be alerted to the situation, asit does not try to calculate the temperature of the objects or cansstored in its inner part in any way, which can cause the refrigerator tochange into energy savings mode, when what was truly required was for itto enter into normal working or recovery mode to cool said cans in caseof high demand of these.

Document US 2005/0177282 by Mason describes a commercial refrigeratorwith an energy savings function which stores rest periods in a memory tothus attempt to predict active and rest times, with which it creates aseries of active and rest patterns, the problem with these types ofsolutions is that they consume too much microcontroller memory, and theycannot be adapted or predict a holiday, as the memory and patterntypically encompass only a week; to encompass a greater time period, alarger memory would be required, the description fails to indicate howthe commercial refrigerator makes known to the microcontroller that itis undergoing high demand, as it does not count the times the door isopened, nor the time it remains open, nor does it consider thetemperature within the refrigerator, it merely takes for granted that insome way the electric control knows said information to then formpatterns of the use.

Another document is U.S. Pat. No. 6,745,581 by King et al whichdescribes a commercial refrigerator consisting of a temperature controldevice connected to an electronic control, the document does notdescribe what the temperature control device refers to, but it can beassumed that it is an electronic or electromechanical system consistingof a temperature sensor in charge of turning the compressor on or offdepending on the target temperature programmed by the user, it appearsthat the functioning of said temperature control device is subject tothe orders of an electronic control, which send a signal from saiddevice to the different actuators such as the compressor, fan orlighting system, the electric control also enables or modifies thetarget temperature of the referred to device depending on the mode inwhich it is functioning, the electronic control requires a movement orpresence sensor, which combined with a sensor on the door of thecommercial refrigerator, detects and stores use patterns to predict whento enter into an energy savings or store closing mode, storing in thememory the time in which movement around the refrigerator is detectedand the times that the door is opened and with these design usepatterns, which are stored in the memory, the system requires storingdata at least 3 weeks; thus a large microcontroller memory is required,it is also noted that the system is also highly expensive to implementgiven that a “normal” temperature control is adhered in some way to anelectronic control for governing the first, highly increasing the costin addition to the microcontroller requiring storage of a large amountof data for processing and determining when in must enter into theenergy savings mode or operate in a normal manner, this also increasesthe control system cost by having to use high capacity storagemicrocontrollers or at least provide the electronic control with thenecessary means to store the data.

BRIEF DESCRIPTION OF THE INVENTION

Commercial refrigerators have traditionally had an energy savings mode,some models can be seen with a timer coupled to an electro-mechaniccontrol system, where the timer allows energizing the system or thecompressor itself within a determined time interval, programmed by theuser, which worked well for a time period, the problem with the abovedescribed system is that it does not know when a low or high demand ofthe product exists, when it was loaded with new product or if there is aholiday or low activity Sunday, or conversely, if it is a high demandweekday or weekend, all depending on the establishment's business styleand model where the commercial refrigerator is found; to avoid multipleadjustments by the user, which is undesirable, leads us to think that acommercial refrigerator which can auto-determine its operation mode isdesirable, as it is a cost saving tool given its energy consumption aswell as human resource efficiency. Present invention aims to provide acommercial refrigerator able to automatically determine its operationmode, depending on the demand of the objects stored within it for adetermined time lapse and thus provide the user significant electricalenergy savings; another objective of present invention is to providesaid commercial refrigerator a new temperature measuring algorithm whichdetermines with a good degree of exactness the temperature of the storedobjects, so that its target temperature value (set point) programmed bythe user, refers to the objects contained inside it, not just to the airtemperature detected by the sensors, making the commercialrefrigerator's operation more precise, now then, the control of presentcommercial refrigerator, does not store large amounts of information tobe able to determine the change of operation mode, this is carried outefficiently counting the time the compressor is turned on in normaloperation mode, as well as in energy savings and recovery mode; based onthis predict when it is likely that demand for the products inside therefrigerator will begin, another peculiarity of present invention isusing two temperature sensors, one placed in the air return precisely atthe evaporator intake, the other placed at the exit of the airevaporator, thus with these two sensors, readings are taken which uponprocessing them allows knowing the temperature of the objects to be soldwithin the refrigerator of present invention with exactness, so that thetarget temperature (set point), set by the user, will refer at all timesto the temperature of the objects found within the refrigerator, not tothe temperature of the air measured at some point in the refrigerator.

DESCRIPTION OF THE FIGURES

FIG. 1 shows a vertical cut of the refrigerator object of presentinvention.

FIG. 2 shows an upper view of the air chamber of the refrigerator objectof present invention.

FIG. 3 shows a block diagram of the peripherals of the electroniccontrol.

FIG. 4 shows a flow diagram of the method object of present invention.

FIG. 5 shows a flow diagram of an alternative embodiment of the methodobject of present invention.

FIG. 6 shows a temperature diagram representing the different operationmodes of the method object of present invention.

FIG. 7 shows a temperature diagram representing the temperature profileobtained by the temperature sensors through time.

DETAILED DESCRIPTION OF THE INVENTION

Present invention lies in the field of refrigerators, particularlycommercial refrigerators, this does not limit that the use of presentinvention, as it may be used in a household refrigerator, industrialrefrigeration chambers or related equipment.

FIG. 1 shows a cross cut of a commercial refrigerator 29, where thecabinet 11 can be seen, which on its outer part is formed by a bodypreferably made of steel and on its inner part by a liner or cover (notshown) preferably made of some thermo-formable thermoplastic, in thespace of these two some type of commercial foam is used which functionsas a thermal insulator; as can be seen in FIG. 1, the cabinet 11 isdisposed with two cavities, the upper cavity being the sales cavity 20,where the objects to be cooled (not shown) are placed (preferablyrefreshment or soda cans), in the lower cavity 21 of the cabinet 11, thecompressor 15 as well as the condenser 16 are found, in an alternativeembodiment of the invention, the condenser 16 or the lower cavity 21 canbe set with a fan 17 (not shown) which aids the forced convection ofsaid elements 15 and 16, which can improve its performance, the referredto fan 17 in an alternative embodiment of the present invention willbecome energized as long as the compressor 15 remains energized, toavoid tedious repetitions it will be understood that each time thecompressor 15 becomes energized, the fan 17 will become energized aswell; now turning our attention to the upper cavity 20 it is alsodisposed with a series of shelves 18 which are preferably manufacturedof steel bars welded and painted in grill manner, this aids insupporting the objects set on them, in addition to allowing the flow ofair through them, which helps in improved convection within the uppercavity; the upper cavity 20 is found covered by a door 10, which ishinged on a vertical side of the referred to cabinet 11 which allowshaving or denying access to the inner part of the upper cavity 20, thereferred to door 10 is set with an interrupter or door opening sensor 28set on some place of the front frame of the upper cavity 20; thereferred to upper cavity 20 is disposed with a lighting system whichconsists with a lighting source 19 such as a bulb or led preferably setover the cover (not shown) of the air chamber, in an alternativeembodiment, the referred to lighting source 19 can be set over the coveror liner 12 within the upper cavity 20, in another alternativeembodiment, the lighting source may be mounted over the door frame 10with such luck that it lights towards the inner part as well as the dooritself, yet in another alternative embodiment, the refrigerator ofpresent invention can additionally be set with an advertisement sign,which is lit by means of a lighting source 19 set behind the referred toadvertisement sign, further, in yet another embodiment, all of the aboveoptions lighting options may be combined or have them allsimultaneously.

Turning our attention to the upper part of the upper cavity 20, we findthe air chamber 22 which is made up of a cover 23, in the inner part ofthe air chamber 22 we find a fan 24 which may be made of blades orsquirrel cage, its function is to suction the air within the uppercavity to force it to pass through the evaporator 25 to be able to carryout the heat transfer and thus provide cold air to the upper cavity, thecold air is injected by the upper back part of the upper cavity 20 suchas shown in FIG. 1; it should be mentioned that the cover 23 has aseries of slits which allow the passage of air towards the fan andanother series of slits which allow for the fluid passage of cooled airemanating from the evaporator 25 towards the upper cavity 20; it shouldbe noted at this point that the evaporator 25 consists on its lower partwith a thawing resistance 32, which may be energized by means of theelectronic control 30 to carry out the thawing of the evaporator 25.

FIG. 2 shows an upper view of the air chamber 22, where the fan 24, theevaporator 25 and the temperature sensors 26 and 27 can be seen, thesensor 26 is set at the air intake emanating from the upper cavity justprior to or in the vicinity of the fan 24, the temperature sensor 27 isset at the exit of the air emanating from the evaporator 25, with suchluck that the temperature sensor 26 detects the air temperature at theintake of the air chamber 22, and on the other hand, the temperaturesensor 27 detects the air temperature at the exit of the air chamber 22,both sensors 22 are connected to an electronic control 30, whichreceives information from the two temperature sensors 26, 27 to processsaid data, such as will be described in detail further below.

Focusing our attention on the electronic control 30, this consists witha power stage, which allows it to connect to the alternating current, tolater pass it through a rectifying stage which will be able to providecontinuous current, preferably 5V CC, which allows feeding themicrocontroller, which preferably is an 8 bits and flash memorymicrocontroller, which receives data from the different sensors andemits signals or pulses to the drivers of the different actuators toenergize or de-energize these according to the method object of presentinvention, the drivers are found at the exit power stage, said driverscan be transistors, traits, relays, among others; the function of theseis to receive a low voltage signal or pulse which allows activating atype of high voltage interrupter which allows the flow of high voltageenergy to the actuators, such as the fans 17 or 24, compressor 15,lighting source or sources 19, thawing resistance 32 etc., so that inorder to repeat tedious repetitions, mention will only be made of theelectronic control which will energize or activate certain actuator tobe understood that this sends a pulse to the driver in particular ofsaid actuator so that this becomes energized; it also occurs this waywith the sensors as these may require some type of signal conditionersuch as an operational amplifier or another type of signal conditioner,which allows granting the microcontroller a signal within its specifiedoperational parameters, thus in order to avoid a multitude of tediousrepetitions, it will merely be indicated that the signals, pulses, dataor by means of the multiple sensors 26, 27, 28, the electronic controlwill acquire the necessary information to process it. In FIG. 3, afunctional block diagram can be seen of the interconnection of theelectronic control 30 with the different actuators and sensors whichmake up the refrigerator object of present invention; whose operationmethod will be addressed below.

Determination of the Temperature of the Objects Within the Refrigerator—

As referred to above, the electronic control 30 can determine thetemperature of the objects to be cooled housed in the upper cavity 20with great exactness, this is achieved by means of the temperaturesensors 26, 27, which detect the air temperature both at the intake aswell as the exit of the air chamber 22 respectively; thus when thecompressor 15 is resting or de- energized and the fan 24 is energized,the electronic control 30 begins to request data from the referred tosensors 26, 27, once the data has been requested by the electroniccontrol 30, this begins to compare the data from the sensors 26, 27 toeach other, in such a way that it calculates the difference of thetemperature between these, once the referred to temperature differencereported by the sensors 26, 27 is stable (i.e. that it has a 1° C.maximum variation); in the preferred embodiment of the presentinvention, the electronic control 30 carries out an average of certainnumber of data per each sensor 26, 27, once having the averages of eachsensor, the referred to electronic control 30 averages them betweenthem; which grants a value highly approximate to the temperature of theobjects 14 housed within the inner part of the upper cavity 20 (see FIG.7), in the preferred embodiment of present invention, the electroniccontrol 30 upon recompiling the data of each sensor 26, 27, while thecompressor 15 is de-energized and the fan 24 energized, once thetemperature readings emanating from the sensors 26, 27 have beenstabilized (such as above described), the electronic control 30 proceedsto average them to obtain an average temperature value of the readingsof the sensors 26, 27, such as can be seen in FIG. 7, wherein thetemperature graphs of the sensors 26, 27, as well as their average, itcan be inferred that while the compressor 15 is at rest and the fan 24is found energized, the temperature obtained from the averaging oftemperature values by the referred to sensors 26, 27 is very similar tothe temperature of the objects placed within the refrigerator 29 (havingan experimental variation less than 1° C. between the averagetemperature obtained by the sensor 26, 27 values and the averagetemperature of the objects housed within the refrigerator 29); it shouldalso be highlighted at this point that such as can be seen in FIG. 7,the differential of the temperature readings of the sensors 26, 27 isalso minimal, where its variation is lesser than 1° C. for most of thetime that the compressor 15 is turned off and the fan 24 is energized;so that in an alternative embodiment the electronic control 30 can takeas a reference temperature the value obtained by the sensor 26, 27jointly or separately. Now then, we can be sure of this thanks to aseries of laboratory tests and studies which helped fine tune thismethod; it should be noted that the location of the sensors 26, 27within the air chamber 22 as well as carrying out the temperaturemeasurements of the sensors 26, 27, ensuring that the door 10 is closed,the fan 24 energized, as well as the compressor 25 de-energized orresting state, are vital to achieving an approximation to thetemperature of the objects housed within the upper cavity 20 issuccessful.

Such as can be seen in FIG. 7, when the compressor 15 is energized, thetemperature values of the sensors 26, 27 are separated, that is, thedifference between them grows or increases, and said differentialdepends on the outer temperature as well as on the construction of therefrigerator 29 itself, thus determining it, can be somewhatcomplicated; thus in the preferred embodiment of present invention, theelectronic control 30 when the compressor 15 as well as the fan 24 areenergized, the door 10 is closed, the electronic control 30 takes as areference temperature, the temperature values obtained by the sensor 27,which is found at the exit of the evaporator, thus the electroniccontrol 30 compares the value of the target temperature vs. thetemperature value obtained by means of the sensor 27, once thetemperature value obtained by means of the sensor 27 is equal or lesserthan the target temperature value (which preferably oscillates at 0°C.), the electronic control will determine to de-energize the compressor15.

Normal Mode of Operation

In the normal mode of operation, the electronic control 30 begins bydetermining the temperature of the objects housed within the inner partof the upper cavity 20, such as above described, once the temperaturevalue of the objects housed within the inner part of the upper cavity 20has been determined it orders a timer to start for a 24 hour periodknown as cycle time, which in a nested manner carries out the time countduring which the compressor 15 is turned on during the normal operationmode—wherein said value will be termed Ton1—it also starts a secondtimer which will count the time that the energy savings mode is active,the referred to value is termed TMN; now then, in a preferredembodiment, the target temperature value of the objects stored withinthe inner part of the refrigerator 29 is already set in the memory ofthe electronic control 30, that is, there is no user interface 31, in analternative embodiment the user by means of the user interface 31 inwhich the alternative embodiment preferably can consist with at leastone pair of screens or LED displays with 7 segments as well as with apotentiometer, encoder, knob or button which allows modifying the valueof the target temperature or “set point”; thus the user interface 31will send the recompiled information by the adjustment means(potentiometer, encoder, knob or button among others), with which thetarget temperature value will be set within the inner part of the cavity20; given that it consists with the target temperature value in theelectronic control 30, the temperature control is carried out in thefollowing manner; with the compressor 15 in resting state, the fan 24 isenergized and the door 10 closed, the temperature of the objects housedwithin the inner part of the upper cavity 20 is determined, such asdescribed above, the electronic control 30 compares the temperature itdetermined for the objects housed within the inner part of the uppercavity 20 (which should oscillate around 3° C.) versus the targettemperature, this is done repeatedly until the electronic control 30finds that the determined temperature of the objects housed in the innerpart is higher than the target temperature; in an alternative embodimentthe electronic control 30 can use the value obtained by one of thesensors 26, 27 either jointly or separately to compare it to the targettemperature (which should oscillate around 3° C.) of the objects housedwithin the inner part of the upper cavity 20 of the refrigerator 29;once this occurs, the compressor 15 is energized which causes theevaporator 25 to lose heat, in turn cooling the air going through it;such as described above the compressor 15 is kept energized until thevalue obtained by means of the temperature sensor 27 is equal to orlesser than the target temperature value, that is: the electroniccontrol 30 when the compressor 15 is energized will acquire the datafrom the sensors 26, 27, from which it will take the temperaturereference value of the objects housed within the upper cavity 20 thetemperature value obtained by the sensor 27 which is near the evaporator25; said temperature value of the electronic control 30 will compare itto the target temperature value (which oscillates around 3° C.) of theobjects set within the upper cavity 20, once the value obtained by thetemperature sensor 27 is equal to or lesser than the target temperature,the electronic control 30 will determine to de-energize the compressor15, in a preferred alternative embodiment, the electronic control 30undertakes an average of the temperature reading it obtains through thetemperature sensors 26, 27, from this average a correction or errorfactor is added algebraically (which can be determined experimentallyand which depends on the particular construction of the refrigerator29), with this the electronic control 30 compares the target temperaturevalue to the average value obtained by the sensors 26, 27, alreadytaking the error or correction factor into account, once this last valueis equal to or less than the target value, the electronic control 30will determine to de-energize the compressor 15; in another alternativeembodiment, the electronic control 30 can maintain the compressor 15energized for a determined time interval (which will depend on theparticular construction of the refrigerator 29 and can be determinedexperimentally) e.g. 30 minutes; in both cases, the electronic control30 will count the time that the compressor 15 remains energized andstore this in the memory.

All this takes place while the door 10 remains closed, once opened, theelectronic control 30 by means of the door sensor 28 determines that thedoor has been opened, this de-energizes the fan 24; also energizes thelighting source(s) 19 set on the commercial refrigerator 29; when theelectronic control 30 detects the door has been closed thanks to thedoor sensor 28, this resumes the activity which it was undertaking priorto the door opening, so that the electronic control 30 returns todetermine the temperature of the objects set in the inner part of theupper cavity 20, or to its cooling mode energizing the compressor 15, inany of its above described embodiments.

Energy Savings Mode

Once the electronic control 30 has determined that for a period of time,(i.e. 30 minutes) the door 10 has not been opened, it then ordersentering into an energy savings mode; here the electronic control 30begins a timer termed TMA which counts the time that the refrigerator 29is in the energy savings mode, it also de-energizes the fan 24 fordetermined periods of time, e.g. 5 minutes, energizing them again for adetermined period of time, e.g. 60 seconds, in which the electroniccontrol 30 will calculate the temperature of the objects housed withinthe inner part of the upper cavity 20, such as described above (in analternative embodiment the electronic control 30 may also de-energizethe lighting source(s) 19); in addition to recovering the time valuewhich the compressor has been energized, within the determined timeperiod (e.g. 24 hours) which the timer has been counting, these data arerecovered to be able to determine the time lapse which the refrigerator29 can remain in energy savings mode, so that once the time hastranspired, then enter into recovery mode.

In the preferred embodiment of the energy savings mode, the electroniccontrol 30 ignores the target temperature value or set point, allowingthe objects stored within it to warm or gain heat, until the electroniccontrol 30 determines that it is time to exit the energy savings modeand start the recovery mode; in an alternative embodiment of the presentenergy savings mode the electronic control may allow a determinedtemperature differential, e.g. 20° C., thus by being in the energysavings mode energizing the fan 24 for a determined time period e.g. 60seconds, with which it determines the temperature of the objects housedwithin the inner part of the upper cavity 20, as described above, thuswhen the electronic control finds it has reached a temperature higherthan the tolerance of the temperature differential it begins itsrecovery mode.

Returning to the preferred embodiment of the present energy savingsmode, the electronic control recovers the time value Ton1, also recoversthe time which the normal operation mode was activated TMN, by dividingTon1/TMN the percentage of time which the compressor 15 was energized isobtained terming said variable as % run1; once % run1 is calculated, theremaining time in energy savings mode termed Trest can be calculated bysubtracting 24-TMN; now then, with Trest time being calculated therecovery time, termed Trec is processed, which is the time required toenergize the compressor 15 so that the refrigerator 29 reaches thetarget temperature of normal operation; calculated by multiplying % run1by Trest; the value of Trest obtained, the electronic control 30continuously compares the Trest value vs. the time value counting thetime that the refrigerator 29 is found in energy savings mode TMA, onceTMA≧Trest the electronic control 30 decided exiting the energy savingsmode to enter the recovery mode.

If the door 10 is opened during the energy savings mode, this causes theelectronic control 30 to return to the normal operation mode. In analternative embodiment of present invention a tolerance of the door 10opening can be established, i.e. if for example the door 10 is open lessthan 3 times for a determined period of time e.g. 15 minutes, therefrigerator 29 will remain in energy saving mode.

Recovery Mode

In the recovery mode the electronic control 30 energizes the compressor15 and the fan 24 and begins to acquire data from the sensors 26, 27 tocompare the determined average temperature vs. the target temperature ofthe normal operation mode; once the objects within the upper cavity 20have reached the target temperature, the electronic control 30de-energizes the compressor 15 to enter the normal operation mode; theelectronic control 30 keeps counting the time during which the door 10has remained closed, until said door 10 is opened, this causes thevariables Ton1, % run1, TMN, TMA, Trec, Trest and the cycle timecounters to be erased to allow calculating new ones as a new cycle isbegun for a determined time period e.g. 24 hours.

Vacation Mode

If after carrying out the recovery mode and the refrigerator 29 beingonce again in normal operation mode, the electronic control detects thatthe door has been closed for an extended period of time without beingopened, e.g. 15 hours, the electronic control 30 determines enteringvacation mode, whereby the electronic control has not erased the Ton1, %run1, TMN, TMA, Trec, Trest values, conserving them to continueoperating in the energy savings mode with these values until door 10 isopened.

Thawing Mode

The electronic control 30 itself in a variable alternative termed TonTotadds or accumulates the time which the compressor 15 remains turned on,this is undertaken for thawing purposes, knowing that certain amount ofworking time of the compressor 15 e.g. every 8 hours of work, theelectronic control 30 energizes the thawing resistance 32 for adetermined time period which allows thawing the evaporator 25 or untilthe exit temperature sensor 27 detects a determined temperature, e.g.30° C.; the thawing mode is preferably carried out when the refrigerator19 is found in energy savings mode, so that when TonTot is greater thanthe number of compressor 15 work hours programmed in the electroniccontrol 30, this will take note of it and enter into energy savings modeto undertake thawing process.

Obviously, a person skilled in the art could find variations to theembodiments herein described, these would have to lie within the scopeand spirit of the following claims; having described present inventionwith sufficient detail, it is found as possessing novelty, inventiveactivity and is found industrially applicable, so that we claim thefollowing claims.

1. A method for operating a commercial refrigerator with a cabinet, thecabinet with at least one first cavity with an inner part, an access tosaid inner part and an air chamber set within the inner part, whereinsaid air chamber set comprises a fan which makes the air pass through anevaporator to carry out a heat transfer, a thawing resistance whichthaws the evaporator, a cover with first slits which allow an air flowemanating from the first cavity towards the inner part of said airchamber and second slits which allow an air flow cooled by theevaporator emanating from the inner part of said air chamber towards thefirst cavity; said method comprising: setting at least two temperaturesensors within the inner part of the air chamber, a first temperaturesensor between the first slit and the fan and a second temperaturesensor set between the evaporator and second slits, said sensors inconnection with an electronic control; collecting first temperature datafrom the first sensor and second temperature data from the second sensorwithin the air chamber; comparing the first temperature data from thefirst sensor to the second temperature data from the second sensor toobtain a temperature value and to calculate stability of the first andsecond temperature data from the comparison; wherein, if said data isstable, averaging said first and second temperature data such that thetemperature obtained is deemed very near the product temperature withinan inner part of a first chamber; and wherein, if the difference betweensaid first and second temperature data increases, de-energizing acompressor by means of the electronic control.
 2. The method accordingto claim 1, wherein once the temperature value of the objects storedwithin the inner part of the first cavity has been determined, start, bythe electronic control, a timer termed as cycle timer, which in a nestedmanner will keep count of the time in which the compressor remainsturned on during a normal operation mode.
 3. The method according toclaim 2, wherein said cycle time is maintained for a 24 hour period. 4.The method according to claim 2, wherein it also starts a second timerwhich counts the time that an energy savings mode is active.
 5. Themethod according to claim 1, wherein the target temperature value of theobjects stored within the inner part of the refrigerator are already setin the memory of the electronic control.
 6. The method according toclaim 1, wherein the target temperature value of the objects storedwithin the inner part of the refrigerator is determined by the user. 7.The method according to claim 4, wherein the energy savings modecomprises de- energizing the fan for determined periods of time andcalculating, by means of the electronic control, the temperature of theobjects stored in the inner part of the upper cavity, to determine thetime lapse at which the refrigerator can be in the energy savings mode.8. The method according to claim 1, wherein the method additionallycomprises energizing both the compressor as well as the fan; acquiringthe data from the sensors to compare the determined average temperatureversus a target temperature of the normal operation mode; wherein, oncethe objects stored within the inner part of the refrigerator havereached the target temperature, de-energizing the compressor to enterinto the normal operation mode; and counting the time that an access hasremained closed, until said access is opened.
 9. The method according toclaim 1, wherein the method additionally comprises determining that anaccess has not been opened for a period of time and conserving theenergy savings mode until the door is opened.
 10. The method accordingto claim 9, wherein the time period is 15 hours.
 11. The methodaccording to claim 1, wherein the method additionally comprisesde-energizing the thawing resistance by means of the electronic controleach pre-determined time period and energizing the thawing resistancewhich allows thawing the evaporator.
 12. The method according to claim11, wherein the pre-determined time period is 8 hours.
 13. The methodaccording to claim 1, wherein the electronic control comprises a powerstage and a rectifying stage.
 14. The method according to claim 13,wherein the rectifying stage grants continuous current to amicrocontroller and a flash memory which receives data from the sensorsand emits pulses to a plurality of drivers of actuators.
 15. The methodaccording to claim 13, wherein the continuous current is 5V.
 16. Themethod according to claim 13, wherein the microcontroller is 8 bits. 17.The method according to claim 13, wherein the drivers are selected fromthe group consisting of at least one transistor, triac, relay, andcombinations thereof.
 18. The method according to claim 13, wherein theactuators drive the fans, a compressor, a lighting source and thethawing resistance.
 19. The method according to claim 13, wherein therefrigerator comprises a user interface.
 20. The method according toclaim 13, wherein the user interface is selected from the groupconsisting of at least one display, potentiometer, encoder, andcombinations thereof.